U.S. Pat. No. 6,269,649 B1 discloses a system for freezing samples under high pressure. The high pressure is necessary in order to prevent the formation of ice crystals in the sample. The sample is located in a sample holder and is clamped into a corresponding sample carrier. The sample carrier is manually transferred into the high-pressure freezing system by the user thereof.
U.S. Pat. No. 5,493,865 discloses a method and an apparatus for high-pressure freezing of biological samples. Before high-pressure freezing, the sample is introduced manually into the sample holder.
At present it is necessary, usually using a stereomicroscope, to fill the small specimen holders that are used in a high-pressure freezing device with a sample. That specimen holder is then installed into a holder for the high-pressure freezing device, and that holder is then inserted into the high-pressure freezing device. Insertion of the holder into the high-pressure freezing device is accomplished manually. The Leica EM PACT brochure discloses a high-pressure freezing device. This system operates with separate pressure and cooling systems. The consequence of this is that the specimen must be threaded in pressure-tight fashion into the sample holder. The Leica EM PACT brochure entitled “Microbiopsy Transfer System” and the Leica EM PACT brochure entitled “Flat Specimen System” disclose several installation aids for specimen holders and tools for manual transfer of the samples, secured in the sample holder, to the high-pressure freezing device.
The brochure of the company styled BAL-TEC AG likewise discloses an apparatus for high-pressure freezing. In this unit, pressure buildup is ensured by way of the cooling medium. Although pressure-tight threading of the specimen holder is not necessary, a loading apparatus and a holder for the specimen carrier are necessary. The time for installation of the specimen carrier and introduction of the specimen carrier into the loading apparatus is also approximately one minute. In addition, the specimen carrier must once again be introduced manually into the high-pressure freezing device.
The disadvantage of the existing art is that more than a minute is required for installation of the samples being examined into a holder provided for them, and for positioning of the holder in a clamping element. In addition, during the threading motion of the clamping element a specific torque must be observed so that the sample to be examined is not mechanically crushed and/or destroyed, which can result in a change in the morphology of the sample to be examined. The sample changes during the aforementioned loading time of approximately one minute, so that the states observed with the optical microscope are no longer present upon examination with an electron microscope. The state of the cells observed with the light microscope differs from the frozen cells. A comparison of the two cells is therefore possible only to a limited extent.